US1725108A - Method and apparatus for making paper - Google Patents

Description

Aug. 20, 1929. A. w. SMITH METHOD AND APPARATUS FOR MAKING PAPER Original Filed March 10, 1926 4 Sheets-Sheet 1 Int/6371702:

Aug. 20, 1929. A. w. SMITH METHOD AND APPARATUS FOR MAKING PAPER Original Filed March 10, 1926 4 Sheets-Sheet 2 r h n 8 m I Aug. 20, 1929. A. w. SMITH 1,725,108

METHOD AND APPARATUS FOR MAKING PAPER Original Filed March 10, 1926 4 Sheets-Sheet 3 WWW Aug. 20, 1929. A. w. SMITH METHOD AND APPARATUS FOR MAKING PAPER 4 Sheets-Sheet 4 Original Filed March 10, 1926 if WM 3 frzverz Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

ALVIN W. SMITH, OF EAST MILLINOCKET, MAINE.

METHOD AND APPARATUS FOR MAKING PAPER.

Application filed March 10, 1926, Serial No. 93,748. Renewed May 4, 1928.

This invention relates to certain improvements in methods and means for preventing the complete breaking of the web in the operation of Fourdrinier paper making machines, so that conditions may be restored to normal without serious delay in production.

In the operation of such machines, when the web breaks or become torn at either edge,

I m the break usually travels completely across the web to the opposite edge and, when a break, or rupture, starts at any intermediate point in the web, it travels from this point to both edges. The average direction the point where it starts is at an angle of about 45 to the edge of the web and towards the direction from which the web is moving. The difliculties arising from a break in the web are well known and are primarily objectionable on account of the great loss in production involved in restoring conditions to normal.

The objects of my invention are to provide an improved method of arresting the breaks in the web of a paper machine, so that they will not travel entirely across the same, and of cutting out the broken portion in a manner to permit the automatic restoration of normal conditions, and, in this connection, to provide an eflicient and practical means for performing such method which is adapted to be applied to any ordinary Fourdrinier machine.

I accomplish these objects by providing means whereby, when a break in the web occurs and begins to travel across the same, as above described, the web will be slit, or cut longitudinally, as it leaves the paper forming wire, along two or more somewhat remote-1y situated lines, preferably located ad- 'jacent each edge of the web, so that, as the break proceeds across the web, it will be intercepted by one of these slits, thereby enabling the operator to cut out the broken portion from this slit to the opposite edge, leaving an unsevered portion, which will act to conductthe end of the cut-out section from the wire to the first press roll.

For a more complete understanding of the method and means which constitutemy invention, reference is made to the accompanying drawings in which in which t e line of the break travels from it is carried over other Fig. 1 is a side elevation of a portion of a Fourdriniermachine, with which my invention is associated.

Fig. 2 is a plan view thereof.

Fig. 3 is a detail sectional view of one of the cutting-01f jet devices.

Fig. 4 is a longitudinal sectional View of an automatic web-slitting device which I em iloy. V

l igs. 5, 6, and 7 are respectively, cross sectional views at the lines wm, 3 3 and e-z, of Fig. 4.

Fig. 8 is a diagram of the electrical connections which I employ.

Fig. 9 is a detail view of a portion of the web-slitting apparatus.

Fig. 10 is a detail sectional View illustrating a step in the process.

Fig. 11 is a view, partly in section, of a suction box controlling means which I employ.

Figs. 12, 13 and 14 are plan views of a portion of a paper web, showing the method of intercepting the break and of restoring the conditions to normal. I

The paper making machine indicated in the drawings does not differ from the ordinary Fourdrinier machine, so that'the parts thereof, which are more directly associated with the invention, are merely indicated.

Such parts comprise the paper forming wire 1, which is carried beneath the top couch roll 2 and about the bottom couch roll 2, and the endless conveyer felt 3, which passes over the guide roll 4, and to which the web, indicated by a dotted line, is delivered from the wire. The felt 3 is indicated as passing over a guide roll 5 to the first pair of press rolls 6, from which point guide rolls, not shown, and returned.

It is customary to provide in machines of this type, a pair of cutting-off jets which are located over the wire in advance of the top couch roll, and in proximity thereto, and, while the herein described method may be performed with only one et of this character, the operation will be facilitated by employing two, as hereinafter described.

The construction employed in this connection is similar to that ordinarily employed, and comprises a pair of parallel pipes 7 and 8, which are mounted at their ends in the for a suitable distance.

frames 9 at each side of the machine in close proximity to each other and at a short distance above the wire 1, close to and slightly in advance of the top couch roll 2. Each pipe has a longitudinal slot in its under side, which extends from end to end thereof and a nozzle 10 is provided in each pipe, which is adapted to project into the slot and to be moved in this position from one end to the other of the pipe. A hose pipe 11 is connected to each nozzle and leads to a water supply which is controlled by a conveniently located valve, as 12.

According to my invention I provide a pair of web-slitting devices, one of which is mounted on each frame directly in front of the first cutting-off jet tube 8, and, as the construction of each is identical, a description of one will suffice. As shown in detail in Figs. 4 to 7 a tube, or casing 14 is rigidly mounted at one end on the frame 9 and projects horizontally over the wire 1 The projecting end of the casing 14 is tightly closed by a cap 15 and an aperture is formed in the under side of the casing adjacent said cap in which a short tube 16, of slightly conical shape is inserted, said tube being arranged to proj ect vertically into the casing to a pointnear the middle thereof, the lower end of said tube being practically flush with the outer surface of the casing and the passagetherethru, tapering from its lower end upward. A nozzle 18 is mounted in the upper side of the casing and extends therethru in line with the tube 16, terminating at a short distance above the upper end of the tube 16 in an orifice which is of slightly smaller diameter than the diameter of the passage thru the tube at its upper end, so thata jet discharged from the nozzle will pass thru the tube without being obstructed thereby, as indicated in Fig. 9. A hose pipe 19 is connected to the nozzle 18 and water under pressure is constantly supplied thereto.

A deflector in the form of a flat plate 20 is mounted on the end of a square rod 21, which is mounted to slide in a guide bracket 22, so that it is held against rotation, said deflector being held by said rod, under normal conditions, between the upper end of the tube 16 and the end of the nozzle 18, but

at a substantial distance beneath the tip of the nozzle and preferably in seating contact with the tube 16, so that the Water which will be constantly discharged from the nozzle 18, will, under normal conditions, strike the upper side of the deflector 20 and be laterally deflected thereby into the casing, and will be prevented from being discharged thru the tube 16 in a jet, as shown in Figs. 4 and 5. A waste aperture 23 is provided in the under side of the casing 14 at a point between the frame on which it is mounted and the adjacent edge of the wire 1, or 'of the Web carried thereon,'so that, under nor mal conditions the water discharged from the nozzle 18 will merely be carried to one side of the web, where it may be delivered to waste, when the deflector is drawn back from the passage thru tube 16, the nozzle 18 will then be free to discharge its jet thru the tube, as shown in Fig. 9. A cylindrical cup 25, of hard rubber, or other suitable, water-proof material, is tightly fitted into the supported end of thecasing 14, so that its bottom end faces the opposite end of the casing and its bottom acts as a partition to prevent the water from flowing beyond the outlet 23. The rod 21 is provided with a cylindrical extension 21 which is slidably fitted in the center of the bottom of the cup and a coil spring 26, on the rod, is interposed between the bottom of the cup and a sleeve 27 on the rod and acts to hold a stop sleeve 28 on the rod at the opposite side of the bottom of the cup against the same. A solenoid core 29 is connected at one end to the rod extension 21 and extends into a solenoid coil 30, so that when the coil is energized, the rod 21 will be drawn back from its normal position of Fig. 4 to the open position of Fig. 9.

' A suction box 32 of common form, is lo cated beneath the felt 3 at a point as close to the point where the web passes ontothe felt as practicable, said box extending from edge to edge of the felt and having a perforated upper side on which the felt rests, as indicated in Fig. 11. A minus pressure gauge 33 is connected to the box, and, under normal conditions of minus pressure holds open a circuit thru the needle 34 thereof. A similar suction box 35 is also preferably located beneath the felt at a short distance beyond the first pair of press rolls 6, and a similar minus pressure gauge 36 is connected thereto and has a contact needle 37.

The electrical connections with the solenoid coil 30 are shown in diagram in Fig. 8, and are indicated in Fig. 1, merely comprising connections 38 and 39 leading from the coil terminals to the terminals of the gauges 33 and 37, and having a signal light 40, and a simple make and break switch 41 therein, which will be normally closed. The circuit is normally kept open by the break at the pressure gauges, but when the pressure falls in either suction box to such an extent that the needle in the pressure gauge connected thereto swings to zero, or to some other predetermined point, the circuit thru the coil will be closed.

A stop sleeve 42, or any other suitable means, may be provided, as a matter of convenience, on each jet pipe 7 and 8, which will be so set thereon that, when one of the nozzles 10 is pushed into the pipe 7 it may be pushed thru the same until it is in a position directly behind the jet orifice in one of the casings 14, at which point it will ongage the sleeve 42 thereon, as shown in F 1g. 3, and, when the other nozzle 10 is pushed into the other pipe 8, it will engage a similar sleeve at a point directly behind the jet orifice of the other casing 14.

' Under normal conditions, therefore, the jet nozzles 10 will be set in the rear, respectively, of the fixed nozzles 18, in the casings 14, the water supply to the nozzles 10 will be shut off and that to-the nozzles 18 will be open, and will be discharged against the deflector 20 and run to waste, as before described. lVhen the machine is being started, the switch 41 will be open and will not be closed until after the web has been carried past the suction boxes 32, 35. \Vhen the web is intact and lies on the felt over the suction boxes, it prevents airfrom being drawn freely thru the felt into the suction box, from which the air is constantly being exhausted, so that an air pressure which is substantially below atmospheric is constantly maintained therein. -Under normal condia tions the pressure in the suction box will be maintained at an approximately uniform point below atmospheric pressure, but, when a break occurs in the web, so that a portion of the felt over the air inlets to the suction box becomes uncovered, then air will be permitted to pass much more freely into the suction box, so that the pressure therein will be, almost instantly, substantially raised. In practice, the relative adjustments of pressure in the suction box and the minus pressure gauge which is connected thereto, is such that, when a relatively small portion of the felt over the suction box becomes uncovered, the consequent increase in pressure will cause such a variation in the position of the needle in the gauge that its needle will swing into engagement with its contact point, so as to close the circuit therethru.

In the operation of a Fourdrinier machine approximately of the breaks in the web occur at or near the point where the web leaves the wire, and a large proportion of the other breaks occur at the first pair of press rolls.

Assuming, therefore, that the machine is operating under normal conditions, and that a break, or tear is then formed at one edge of the web as it leaves the wire, so that, by the time the opening, formed in the web by the break, reaches the first suction box- 32, it has lengthened to some extent in an oblique direct-ion towards the opposite edge, thereby causing a substantial portion of the felt over the suction box to become uncovered, as indicated in Fig. 12-. The instant this occurs the pressure in the box 32 is increased, so that the needle 34 swings into contact with the other terminal of the gauge, closing the circuit thru coils 30,.thereby causing them to become energized, so that the rods 21 will be drawn back againstthe action of the springs 26 until the deflectors 20 are drawn to their inoperative'position of Fig.9, permitting the jets discharged from the nozzles 18 to pass thru the tubes 16, so that a jet fromeach nozzle 18 is discharged onto the -web directly beneath it. As a result, these jets will immediately begin to cut slits in the web, which will extend parallel to the edges thereof, each slit being formed at a predetermined distance. (preferably about 2, when the web is 12 wide), from its adjacent edge, according to the positions in which the nozzles 18 are fixed, as before explained. A break in the web will travel at an average angle of approximately 45 to the edge of the web from the point where the break starts towards the direction from which the web is moving. The break will not, usually, however, progress in the direction from which the web is moving any faster than, or as fast asthe speed at which the web is moving. The point at which each longitudinal slit starts, will, of course, travel at the speed of the web, so that the line of the break and the line of the slit at the opposite edge of the web will progress somewhat convergently and will usually meet at some point, as indicated in Fig. 13, which will vary according to circumstances. While in some instances the break will travel so rapidly that it will not 1661 the slit, at the opposite edge of the web,

while the rest of the web will usually either.

pass beneath the wire or be carried on by the felt to the first press rolls and then pass up about the upper press roll, where it will be removed by the usual doctor 45. From the time the break begins to pass over the suction box, some portion of the break will continue over the suction box, so that the restoration of the normal minus pressure therein will be prevented and the automatic jets from nozzles 18 will continue to operate on the Web. As soon' as these jets start in operation, the signal lights 40 in the circuit will be lighted, so that the machine tender will be at once notified. To restore conditions to normal he will first open the valve leading to the nozzle 10 which is in the rear of the automatic jet which is making the slit which intercepted the break, so that a jet will then be discharged from this nozzle 10 into the slit made by the automatic jet, as shown in 10. Then he will break the circuit by opening the switch 41, so that the spring 26 will immediately be permitted to move the rod 21 back to its normal position,

10. The machine tender will then move this nozzle 10 to the opposite edge of thesheet from that next which the intercepting slit was, adjacent, at a speed which will cause the jet therefrom to cut the web as it is moved. As a result it will make an oblique cut to the opposite edge, as indicated in Fig. 14, thus cutting out the broken portion of the web and leaving the web in such acondition that it will automatically restore itself to normal conditions, the oblique portion being supported and guided at its small end, and being carried onto the first felt 3 and on thru the machine Without further assistance from the machine tenders. The broken portion of the web is thus cut out, and conditions are restored without delay in production, except during the time taken to cut the broken portion. As soon as the web begins to run over the suction boxes again, the minus pressure therein will be restored and then the automatic apparatus will be reset by closing the switch 41.

In case a break occurs at the first press rolls, the automatic operation above described will be repeated by the closing of the circuit thru the gauge 36. As the web is then drier, the break will 'not travel as rapidly as when it occurs at the wire, so that in many instances the break will be intercepted as before described. It will be understood'that, if the break starts at either edge, it will be intercepted by the longitudinal slit at the opposite edge and that if it starts at an intermediate point, it will progress towards both edges and may be intercepted by one or the other of the slits, or possibly by both the slits.

It w1ll be understood that it is quite immaterial at which side of the automatic jets 18 the cutting off jets 10 are placed, i. e., whether in front or" in the rear thereof, as the cutting off jet will be started in operation before the automatic jets are shut off. It will also be understood that various other changes in details may be made without materially afi'ectingthe results secured, or the method of operation above described, al-

though the apparatus above described is believed to be by me more efiicient and effective than any other of which I am aware. For example, it will be apparent that the element of time between the time when the break in the web first starts and the time when the formation of the longitudinal slits begin, is of the utmost importance, for, if the slitting action does not begin as quickly as possible the break will pass the line of the slit which might intercept it. For this reason the provision of means for providing a constantly discharging nozzle, the jet from which is normally deflected to waste, is particularly advantageous as compared with a valve in the nozzle which would be automatically opened, for the deflector plate may be pulled to one side of the jet, close to the web, almost instantly, so that the jet will be immediately effective in forming the slit, while it would necessarily require more time to operate a valve and the action would be more likely to be stopped or retarded by friction.

Also other means may be devised, than the above described pressure controlled means connected to the suction box, for detecting the break in the web, so as to close the circuit and set the automatic jets in operation, but the above described means is believed to be particularly effective in quickly detecting the break and in causing certain and immediate closing of the operating circuit.

While it is necessary to locate the automatically operating jets over the paper forming Wire to interce t fractures occurring between the wire anc the first press rolls, and while the web may be cut by the water jets more conveniently, easily and eflectively at this point than at other points, yet, it is considered to be within the scope of my invention to operate the automatic and cuttingoif jets at other points, as for example between the first and second felts, at which points slits would be formed which would be more likely to intercept fractures occurring at the second press roll than would slits formed on the wire.

I claim:

l. The method of arresting the progress of a fracture, when it occurs in the web of a paper making machine of the type described, and of restoring the operating conditions to normal, which consists in discharging a fluid jet against the moving web at a point adjacent the edge of the web most remote from the point from the starting point of the fracture, to form a longitudinal slit in the web which will cross the line in which the fracture is proceeding and intercept the same, placing in action asecond fluid jet in line with the slit thus formed and adjacent,

the first named jet, so as to continue the formation of the slit when the operation of the latter is discontinued, then discontinuing the operation of the first named jet and then cutting the web across from the slit to the more remote edge of the web by means of the second named jet.

2. The method of arresting the progress of a fracture, when it occurs in the web of a paper making machine of the type described, and of restoring the operating conditions'to normal, which consists in dischargin a pair of fluid jets against the moving we at points adjacent its edges to form a pair of similarly located longitudinally extending slits therein, one of which will extend across the line in which the fracture is progressing, so as to intercept the same, then discharging a fluid jet in the line of the slit which has intercepted the fracture adjacent the jet which is forming the slit, so as to continue the formation thereof, then discontinuing the operation of both of the first named jets, and then cutting the web across from the intercepting slit to the more remote edge of the web by means of the second named jet 3. In a paper making machine of the type described, a pair of fluid jet nozzles fixed adjacent the web, to form a longitudinal slit therein adjacent each edge thereof as it passes the nozzles, controlling means normally preventing operative action of said nozzles and automatically causing operative action thereof when a fracture occurs in the web, whereby the progress of the fracture across the web may be intercepted by one of said slits, and manually controlled means for continuing the formation of either slit and for cutting the web therefrom to the opposite edge.

4. In a paper making machine of the type described, a pair of fluid jet nozzles fixed adjacent the web, to form a longitudinal slit therein adjacent each edge thereof as itpasses the nozzles, controlling means normally preventing operative action of said nozzles and automatically causing operative action thereof when a fracture occurs in the web, whereby the progress of the fracture across the web may be intercepted by one of said slits, manually controlled means for moving said nozzle controlling means to discontinue the operative action of said nozzles, and fluid jet devices for continuing the formation of either slit, when the operative action of said nozzles is discontinued and for cutting the web from the slit to its opposite edge from the slit.

5. In a paper making machine of the type described, a pair of fluid jet nozzles fixed over the web in position to cut a longitudinal slit therein adjacent each edge thereof, normally operative controlling means for preventing cutting action of the fluid discharged from said nozzles, and means for automatically moving the controlling means of each nozzle to an inoperative position upon movement of a fractured portion of the web past a redetermined point, whereby the progress 0 the fracture across the web may be intercepted by one of the slits thereby formed.

6. In a paper making machine of the type described, a fluid jet nozzle arranged to cut the web while carried by the machine, normally operative controlling means for preventing operative action of said nozzle, pressure controlled operating means for moving said nozzle controlling means to an inoperative position, an air chamber in which an air pressure different from atmospheric pressure is normally maintained, said chamber having an air passage leading thereto ar ranged to be obstructed by the web as it is carried thru the machine, and connections between said air chamber and said pressure controlled means for causing operative action of the latter when the air pressure in said chamber is substantially varied by the movement of a fractured portion ofthe web across said air passage.

7. In a paper making machine of thetype described, a fluid jet nozzle arranged to cut the web while carried by the machine, normally operative controlling means for preventing operative action of said nozzle, an air suction device having an air inlet arranged to be obstructed by the web as it is carriedalong in the machine, and pressure controlled means for moving said nozzle controlling means to an inoperative position arranged to be operated upon an abnormal increase in pressure in said air suction device due to the passing of a fractured portion of the web over said inlet.

8. In a paper making machine of the type described, a fluid jet nozzle arranged to cut the web while carried by the machine, normally operative controlling means for preventing operative action of said nozzle, electrically operated means for moving said nozzle controlling means to an inoperative position, pressure controlled means for controlling said electrically operated means, an air suction device having an air inlet arranged to be obstructed by the web as it is carried along in the machine and connections between said air suction device to said pressure controlled means, whereby the latter will be moved to cause operative movement of said electrically operated means upon abnormal increase in pressure in said air suctidn device due the passage of a fractured portion of the web past said air inlet.

9. In a paper making machine of the type described, a normally inoperative fluid jet apparatus for cutting the web while carried by the paper forming wire, conveying means for receiving the web from the wire, a suction box so arranged that the web obstructs the entrance of air thereto throughout the width of the web as it is carried by said conveying means, whereby a partial vacuum may be maintained in the box while the web portion passing the same is intact, and pressure controlled means connected to said suctionbox and arranged to be actuated to cause operation of said fluid jet apparatus when the air pressure in said box is abnormally increased by the admission of air thereto 'thru a fractured portion of the web.

10. In a paper making machine of the type described, a fluid jet nozzle arranged to cut the web while supported in the machine,

- pressure in said box by the admission of an abnormal volume of air thereto thru a fractured portion of the web passing thereover, and manually controlled means for returning said nozzle controlling means to its normal position without restoring the partial vacuum in the box.

11. In a paper making machine of the type described, a fluid jet nozzle arranged in position to cut the web while carried along by the machine, normally operative controlling means for preventing operative action of fluid discharged from said nozzle', a suction box extending beneath the web from edge to edge thereof and having the ingress of air thereto obstructed by the web throughout the width thereof, normally permit-ting a partial vacuum to be maintained in the box while the entire web portion passing thereover remains intact, and pressure operated means connected to the box and arranged to cause movement of said controlling means to an inoperative position upon substantial increase in air pressure in the box due to the admission of air thereto thru a fractured portion of the web.

12. In a paper making machine of the type described, a nozzle fixed in position to discharge a fluid jet onto the web and slit it longitudinally as it passes the nozzle, means to provide a constant fluid discharge from said nozzle, means to deflect the fluid as it is discharged from said nozzle to prevent impact thereof on the web, and automatic means arranged to move said deflecting means to permit the fluid discharged from the nozzle to slit the web, when a break occurs therein, whereby the progress of the break across the web may be intercepted by the slit.

13. In a paper making machine of the type described, a casing mounted on the frame in position to extend horizontally over the web, as it is carried thru the machine, and having an orifice in its under side, a nozzle opening within the casing in position to direct a water jet thru the orifice onto the web, a deflector having means to hold the same between the nozzle and the orifice, to deflect the jet discharged from the nozzle into the casing, means within the casing to prevent the Water deflected into the casing from passing thru the orifice and for permitting it to escape therefrom at the edge of the web, and automatic means for moving said deflector to one side of the nozzle arranged to be actuated when the web becomes fractured, whereby a slit may be formed in the web which will intercept the fracture as it extends across the web.

14. In a paper making machine of the type described, a tubular casing arranged to extend horizontally over the web, said casing having an orifice in its under side opening to the web at a distance from its edge, a nozzle opening within the casing in position to direct a water jet thru said orifice onto the web, to out a slit therein and having connections whereby water may be constantly supplied thereto, a tube forming a continuation of said orifice and extending within the casing towards said nozzle, a deflector having means for normally supporting the same in position to close the upper end of said tube and deflect water discharged from the nozzle into the casing, means permitting escape of the water from the casing beyond the edge of the web and automatically operated means for moving said deflector out of its deflecting position arranged to be set in action upon rupture of the web.

15. In a paper making machine of the type described, a tubular casing having an orifice opening to the web at a distance from itsv edge, a nozzle opening within the casing in position to direct a water jet thru said orifice onto the web, to cut a slit therein, and having connections whereby water may be constantly supplied thereto, a rod reciprocally mountedin said casing and having a deflector at one end, means normally actuating said rod to hold said deflector in position to deflect water passing from said nozzle into said casing and prevent slitting action thereof on the web, electromagnetic means for moving said rod to carry said deflector to an inoperative position, and automatic means for causing energization of asid electromagnetic means when the web is ruptured.

16. In a paper making machine of the type described, a pair of fluid jet nozzles arranged to form a slit in the web adjacent each edge thereof as it is carried by the machine, electrically operated controlling means for each nozzle normally acting to prevent operative action of said nozzles, conveying means for the web, a suction box located beneath said conveying means and extending from edge to edge of the web, whereby entrance of air to the box is obstructed by the web and a partial vacuum may be maintained therein so long as the web portion passing thereover is intact, a pressure operated device connected to said box, and a switch for said nozzle controlling means arranged to be actuated by said pressure operated device,

whereby, on abnormal increase in pressure within the box, said switch will be operated to cause actuation of said controlling means and permit operative action of the nozzles.

17. In a paper making machine of the type described, a pair of fluid jet nozzles arranged to form a slit in the Web adjacent each edge thereof as it" is carried by the machine, electrically operated controlling means for each nozzle normally acting to prevent operative action of said nozzles, conveying means for the web, a suction box located be neath said conveying means and extending from-edge to edge of the web, whereby entran'ce of air to the box is obstructed by the web, and a partial vacuum may be maintained therein so long as'the web portion passing thereover is intact, pressure operated device connected to said box, a switch for said nozzle controlling means arranged to be actuated by said pressure operated device, whereby, on abnormal increase in pressure within the box, said switch will be operated to cause actuation of said controlling means and permit operative action of the nozzles, a manually controlled fluid jet device adapted to be set in position to continue the formation of either slit formed by said nozzles and movable to cut the Web from the slit to the,

more remote edge of the web, and a manually controlled switch for causing said nozzle controlling means to be returned to its operative position before the air pressure in the suction box is again reduced to normal.

18. In a paper making machine, an air chamber having means for exhausting the air therefrom and having an air inlet thereto arranged to be obstructed by the web as it is carried by the machine, whereby a partial vacuum will be normally maintained in said chamber and the air pressure therein will be substantially increased when a fracture occurring in the web permits the ingress of an increased volume of air thereto, and a pressure operated device connected to said air chamber and arranged to be normally held inoperative while said partial vacuum is maintained in the chamber, and to be oper atively actuated upon the substantial increase in pressure therein.

19. In a paper making machine, means for detecting a break in the web, comprising an air chamber having an air inlet thereto opening to the web thruout the Width thereof, whereby the entrance of air to the chamber is normally obstructed by the web as it is carried by the machine, to permit a partial vacuum to be normally maintained in said chamber and the pressure therein to be substantially increased when said air inlet becomes partly unobstructed by the formation of a break in the web, and a normally inoperative pressure controlled device connected to said chamber and arranged to be operatively actuated when the pressure in said chamber is substantially increased above normal.

20. The method of detecting a break in the travelling Web of a paper making machine and of setting into operation means for arresting the progress of the break, so that its continuity may be restored to normal, which consists in so controlling the action of a pressure operated device by means of the variations in pressure in an air chamber, in which a partial vacuum is normally maintained and thesair entrance to which is partly obstructed by the web as it is carried thru the machine, that said device will normally be inoperative and will be operated by an abnormal increase in pressure in said chamber due to the admission of air thereto thru a break occurring in the web. I,

In testimony whereof, I have signed my name to this specification.

ALVIN W. SMITH.

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